Gas turbines are widely used in industrial and power generation operations. A typical gas turbine includes a compressor section, a combustor downstream from the compressor section, and a turbine section downstream from the combustor. A working fluid such as ambient air flows into the compressor section where it is compressed before flowing into the combustor. The compressed working fluid is mixed with a fuel and burned within the combustor to generate combustion gases having a high temperature, pressure, and velocity. The combustion gases flow from the combustor and expand rapidly through the turbine section to rotate a shaft and to produce work. The combustion gases are then exhausted from the turbine section through an exhaust diffuser positioned downstream from the turbine section.
The exhaust diffuser typically includes an inner shell and an outer shell that is radially separated from the inner shell to form an exhaust flow passage through the diffuser. One or more generally airfoil shaped diffuser struts extend between the inner and outer shells within the exhaust flow passage to provide structural support to the outer shell and/or to an aft bearing that supports the shaft. Aerodynamic performance of the exhaust diffuser is an important component of overall gas turbine output and heat rate.
As the combustion gases flow through the exhaust flow passage and across the diffuser struts, overall aerodynamic performance of the gas turbine is impacted. As a result, diffuser strut designs are typically optimized for base-load or full-speed/full-load operation of the gas turbine to improve gas turbine efficiency during regular and peak power demands. However, the gas turbine may also operate in a part-load condition which results in increased swirl of the combustion gases exiting the turbine and entering the exhaust diffuser. The increased swirl triggers flow separation from a suction side of the diffuser struts which impacts the aerodynamic performance of the gas turbine during part-load operation and has an impact on overall gas turbine efficiency. Therefore, an improved diffuser strut design which reduces flow separation across the diffuser struts when operating the gas turbine outside of base-load and/or full-speed/full-load operation would be useful in the art.